The proposed research is an outgrowth of prior work on the varied functions of punishment in discrimination learning, in particular, punishment's function as a "distinctive cue" which can facilitate performance when administered for the rewarded response (shock-right training). In an extension of this work focusing on conditioned punishment, Pavlovian conditioning was used to impart neutral stimuli with "acquired distinctiveness," e.g., through conditioned fear and its feedback component. This research has shown that a conditioned fear excitor (CS plus) for the food-rewarded response (fear-right training) will facilitate performance, in contrast to the suppression obtained with a CER procedure, and conversely, that a conditioned fear inhibitor (C S minus) similarly applied will retard performance. Because these effects are reversed when the CSs are administered for the non-rewarded response, they suggest that a CS has the primary function of signaling the occurrence (CS plus) or nonoccurrence (CS minus) of one type of reinforcer (e.g., shock) and that such a function can be readily transformed in the context of a qualitatively different reinforcer (e.g., food) to signal the presence or absence of the new reinforcer. Thus, depending upon the relationship of its signaling property to the presence or absence of reward, an aversive CS will function either as a conditioned reinforcer or as a conditioned punisher. The proposed research assesses the relationship of the signaling and affective (aversive-appetitive) properties of a CS by investigating those conditions under which aversive CSs will either facilitate or retard performance in appetitive discrimination learning. Such research is addressed to (a) the parameters of Pavlovian conditioning, (b) the conditions of appetitive discrimination training, and (c) their interrelationship, and will be extended to CER and related methodologies.